The field of this invention is that of devices for interrupting an electrical circuit in response to the occurrence of an overload current in the circuit, and the invention relates more particularly to low cost, resettable, current-responsive circuit interrupting devices which are sufficiently compact to be accommodated in an automotive fuse block in substitution for fuses for protecting an automotive electrical system.
Automotive electrical systems typically include one or more fuse blocks to accommodate the relatively large number of fuses necessary for protecting different portions of the circuit against current overloads. In one desirable fuse block arrangement, fuse terminals and an integral fuse element connecting the terminals are blanked from a flat metal strip and enclosed in a thin wafer-like housing. A large number of such thin fuses can be very compactly accommodated in slot-like openings in a small fuse block to provide one-shot protection for automotive circuits by interrupting the circuits in response to occurrence of selected current overloads. The fuses provide good response over the wide range of ambient temperatures encountered in the automotive environment, are manufactured at low cost, are easily adapted to provide desired high current capacity, are very compactly accommodated in a fuse block, and also permit convenient diagnostic testing of the circuits via the fuse terminals. Resettable circuit interrupter devices or circuit breakers have been proposed for performing this protective function for automotive circuits but previously known circuit breakers intended for this purpose have been expensive and bulky and have usually required separate discrete connection into each portion of the automotive circuit to be protected. It would be desirable if circuit interrupter devices used to protect some of those automotive circuits were resettable for restoring the circuit functions after a fault condition has been corrected or to permit the circuit to operate at least intermittently for safety purposes for example until action can be taken to correct a fault condition, particularly if such circuit interrupting devices could be made at sufficiently low cost and could be compactly accommodated in existing automotive fuse blocks or the like in substitution for known fuses.